TEM structural studies on Se+ implanted GaAs

(100) GaAs slices were implanted with 450 keV Se+ ions with the slices at 2000C. Ion doses of 1013, 1014, 5 x 1014 and 1015 cm-2 were used, and the specimens subsequently annealed at 400, 500, 600, 700 and 8000C using Al as an encapsulant. TEM studies of the damage were made using 'plan' and '900 cross-sectional' specimens. Two different types of damage occurred. 'Surface' damage extended from the surface to a depth of approximately 600 A, and consisted of fine irregular structure at low annealing temperatures and dislocation lines at high annealing temperatures. 'Interior' damage occurred in bands beneath the surface at doses of 1014 cm-2 and greater, and consisted of clusters at low annealing temperatures and dislocation loops at high annealing temperatures. In some instances the 'interior' damage was present in two discrete bands. The damage often extended to depths of 3 to 4 times the LSS range, and the formation of damage observable by TEM was often retarded when the implanted ion concentration was high. (author)